For years metal cans have been used to pack and ship a multitude of products for industrial and consumer consumption. Traditionally, such cans comprised a cylindrical metal container body with a metal end seamed upon and closing one or both ends of the body. More recently, others have suggested plastic container bodies sealed with metal ends.
There have been difficulties, however,in applying the hard metal ends to the softer plastic container bodies. For instance, when one tries to seam a metal end onto a plastic body, the sharp metal rolled edge often cuts through the softer plastic material negating an effective seam. Moreover, special exterior molds and supports are usually required to support or envelope the container body to prevent it from being crushed when conventional tooling force is applied during the seaming process.
Among other objectives, the purpose of this invention is to overcome the two above-mentioned difficulties. By designing the container flange with a specific tapered shape, the resulting seam develops a balanced pressure distribution in the body hook. Further, by providing a tapered body and a sharp radius at the juncture of the body flange and the remainder of the container body, it is possible to perform the seaming operation with conventional techniques and tooling. Special supporting molds can be eliminated because the specifically shaped plastic body, itself, can withstand the resultant smaller seaming forces without danger of buckling.
Other objects and advantages of this invention will become obvious to those skilled in the art upon consideration of the following detailed description and the drawings illustrating a preferred embodiment.